The thing is that these creatures belong to the order Chiroptera, while rodents are of an absolutely different order. Ambiguity might be caused by the fact that these flying creatures have probably descended from a land animal. Some species are able to climb trees and even to swim! Bats and rodents belong to separate orders, although a bat's snout does have a lot in common with a rodent's snout, doesn't it?

More Info: en.wikipedia.org